Description:

Objective:

Studies are currently being conducted to determine whether HAB algae enter the planktonic food web through predation either by protists or metazoans such as crab larvae. The question of whether the HAB prey being fed to these predators is toxic is the focus of this project. Toxicity of HAB algae will be measured using feeding experiments with the marine rotifer, Brachionus plicatilis and measuring endpoints such as swimming speed, egg production, reproductive mode and mortality. This may lead to the development of a real time bioassay to determine the toxicity of HAB algae. Current bioassays are difficult, time consuming and expensive. Development of a bioassay using rotifers will lead to easier, short and inexpensive bioassays. The second part of the project will use rotifers reared on HAB algae to feed larval crabs. Whether or not crab larvae will ingest toxic rotifers will comprise this part of the project. If ingested, growth of larval crabs will be recorded and toxicity of HAB will have been passed from HAB cells up the planktonic food web to crab larvae.

Goal 1) to use rotifers as a vector of transporting toxicity up the planktonic food web and record effects of toxicity on brachyuran crab larval development. Goal 2) to develop a real time bioassay to measure toxicity of HAB algae retained in culture.

Harmful algal bloom algae have been collected from seas and lakes all over the world and maintained in laboratory cultures for research. Whether or not these HAB algae are still toxic is hard to answer with current time consuming and expensive tests. This fellowship will help in assessing the necessary steps that may lead to the development of a new bioassay to test HAB toxicity using marine rotifers. This will help determine whether or not HAB algae enters the planktonic food web using larval crabs. If rotifers eat the HAB algae and crab larvae eat the toxic rotifers, this will confirm how HAB algae enters the food web and a new bioassay will have been developed to test HAB toxicity.

Approach:

This project will consist of several feeding experiments using HAB dinoflagellates and the marine rotifer, Brachionus plicatilis. Toxicological endpoints such as egg production, reproductive mode, swimming speed, and mortality of rotifers fed toxic dinoflagellates versus rotifers fed non-toxic dinoflagellates will be measured. Ingestion will be confirmed using dinoflagellates stained with a fluorescent dye and epicflourescent microscopy. CHN analyses will be conducted on rotifers to measure Carbon concentrations. Rotifers reared on toxic algae will be fed to crab larvae and ingestion rate, growth rate and crab larval instar levels reached will be recorded and compared to controls fed non-toxic rotifers.

Expected Results:

Preliminary experiments have shown rotifers will ingest some strains of HAB and continue to reproduce normally (asexually). Swimming behavior, egg production and mortality were affected by high concentrations of HAB. Therefore, I expect HAB toxicity may be tracked up the planktonic food web to larval crabs and to develop a bioassay to measure toxicity of HAB strains in culture.

The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.